Jacking mechanisms

ABSTRACT

Jacking mechanism to be used in connection with supporting legs for raising or lowering a marine platform as employed, for example, in offshore barge-type equipment. The jacking mechanism combines the action of hydraulic cylinders with a power-driven threaded screw to effect climbing relative to a leg structure of a suitable support tower. Hydraulic cylinders are mounted at one end on a suitable support and at the opposite end connected with a head having means for detachable pin connection with a track along which the head can travel. The pair of hydraulic cylinders or jacks are located symmetrically of each leg section so as substantially to balance the load applied thereto. Movement of the head is opposed by the action of a threaded ram which acts primarily as a safety feature at all times.

United States Patent [72] Inventor John R. Sutton P. O. Box 32, Beaumont, Tex. 77704 [21] Appl. No. 840,807 [22] Filed July 10, 1969 [45] Patented Sept. 14, 1971 Continuation-impart of application Ser. No. 678,397, Oct. 26, 1967, now Patent No. 3,495,806, dated Feb. 17, 1970.

[54] JACKING MECHANISMS 16 Claims, 9 Drawing Figs.

[52] U.S. Cl 254/106, 254/93 A [5 1] Int. Cl E02d 21/00 [50] Field of Search 254/l05l07 [56] References Cited UNITED STATES PATENTS 3,082,607 3/1963 Sutton 254/105 X 3,245,658 4/1966 Sutton 3,396,945 8/1968 Schreier Primary Examiner- Robert C. Riordon ABSTRACT: .lacking mechanism to be used in connection with supporting legs for raising or lowering a marine platform as employed, for example, in offshore barge-type equipment. The jacking mechanism combines the action of hydraulic cylinders with a power-driven threaded screw to effect climbing relative to a leg structure of a suitable support tower. Hydraulic cylinders are mounted at one end on a suitable support and at the opposite end connected with a head having means for detachable pin connection with a track along which the head can travel. The pair of hydraulic cylinders or jacks are located symmetrically of each leg section so as substantially to balance the load applied thereto. Movement of the head is opposed by the action of a threaded ram which acts primarily as a safety feature at all times.

PATENTEU SEP1 419?! SHEET 1 OF 5 INVENTOR JOHN msarrazv,

ATTORNEYS PATENTED SEP14|97I 3504.683

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ATTORNEYS PATENTEU SEP1 4 191a SHEET 5 [If 5 0 a at, a m 6 m J I 5 1 g 1 E m o 1/ 3 aw b a 9 l: .7 5 k a mi N ATTORNEYS JACKING MECHANISMS This application is a continuation-in-part of my prior application for Apparatus for Raising and Lowering an Offshore Platform, filed Oct. 26, 1967, Ser. No. 678,397, now US. Pat. No. 3,495,806, granted Feb. 17, 1970.

SUMMARY OF THE DISCLOSURE This invention relates to improvements in jacking mechanisms adapted for use particularly for offshore platforms for raising and lowering the latter relative to support columns.

Ofishore platform-elevating equipment, as proposed heretofore, is set forth in my prior U.S. Pat. No. 3,245,658, dated Apr. 12, 1966, which is referred to as an example of the type of mechanisms which has been suggested for use and in some instances used heretofore. Each barge or platform has a plurality of legs. The legs can be pipe columns or fabricated structural legs using pipe or structural steel members.

A jacking mechanism is provided for each leg, mounted for relative movement therealong. These jacking mechanisms are synchronized so as to effect relative raising and lowering movements of the barge or platform with respect to each of the legs.

Various jacking mechanisms have been proposed heretofore, but these have not been altogether satisfactory, either because of the complexity and expensiveness thereof or for lack of proper and desired operation in effecting the relative raising and lowering movements of the barge or platform with respect to the leg and they have not embodied safety factors desired in this critical operation.

One object of this invention is to simplify and improve the construction of the jacking mechanism to effect relative climbing motion between the column and platform with a minimum of structure and secure connection with the operating parts.

Another object of the invention is to provide for a balancing of hydraulic pressure in effecting step-by-step jacking motion between a leg and a platform and incorporating a holding means as a safety factor in the event of hydraulic pressure failure.

Still another object of the invention is to provide for use in a jacking mechanism of a pair of hydraulic jacks connected with the jack head that is to be pinned step by step to the jack track, in relation to a hydraulic-threaded ram jack acting on the head in cooperation with the lower hydraulic jacks for combined compression, thrust and tension pull on the jackhead in load-lifting operation.

These objects may be accomplished, according to certain embodiments of the invention, by mounting hydraulic cylinders upright in pairs on different sides of each chord of a support column, forming the leg with each pair of hydraulic cylinders connected at their upper ends with a head, having means for pin connection step by step with a jack track. A single hydraulic threaded ram jack is also connected with the head and extends thereabove, being carried by a stationary support thereover, moving up and down to effect movement of the head.

BRIEF DESCRIPTION OF DRAWINGS These embodiments of the invention are illustrated in the accompanying drawings, in which:

FIG. 1 is a perspective view of the jacking mechanism in its relation to a barge or platform, shown partly in section, without explicit details shown;

FIG. 2 is a side elevation of the jacking mechanism with more explicit details of the mounting assembly shown;

FIG. 3 is a view at right angles thereto;

FIG. 4 is a horizontal section through one of the legs, showing two pairs of support cylinders therefor as used for the continuous jacking system;

FIG. 5 is a detail cross section showing the spherical seat mounting for the head end of the hydraulic threaded ram on the jack head;

5 jacks each working in unison in a continuous jack system;

FIG. 8 is a side elevation of the jacking mechanism according to FIG. 6 and holding means for a single action jacking system; and

FIG. 9 is a side elevation thereof at right angles thereto.

DETAILED DESCRIPTION OF DISCLOSURE The invention is described in connection with a suitable floatable barge or platfonn which is illustrated in FIG. 1 as having multiple decks, generally indicated at 2 and 3. A single leg or a suitable number of legs extend through openings 4 in the decks, which legs may be of any suitable or desired shape as, for example, triangular, as illustrated in FIG. 6, or circular, as shown in FIG. 7. Each leg has a plurality of leg sections connected therewith which likewise may be cylindrical or polygonal and provided with one or more tracks for effecting stepping action of the jacking mechanism with respect thereto. One of the leg sections is illustrated at 5 in FIG. 1 and provided with tracks 6 and 6' on different sides thereof.

One form of the invention involves a continuous jacking system which is illustrated in FIGS. 1, 2, 3, 4, and 7. This system uses two sets of two-way hydraulic cylinders connected to sliding blocks.

A pair of cylinders 7 is located on each opposite side of the leg section 5, symmetrically with respect to the track 6 on each side thereof. A second pair of cylinders 8 is disposed in front of each leg section 5, according to the illustration in FIG. 1, the cylinders 8 also being symmetrical with respect to the adjacent track 6'.

The cylinders 7 and 8 are shown as having the cylinder end thereof mounted on the deck 2 upon mounting pads 9 and pivoted thereto at 10 for freedom of swinging movement with respect to the deck. These mounting pads form clevises for connecting the cylinders with the deck.

Each of the cylinders 7 and 8 has a piston mounted therein with a projecting end. The pistons of the cylinders 7 are pivotally connected at 11 with cars 12 on a sliding head 13. The pistons on the cylinders 8 are pivotally connected at 14 with ears 15 on a sliding head 16.

The heads 13 and 16 have portions 17 and 18, respectively, which extend in embracing relation with the adjacent side faces of the tracks 6 and 6. The portions 17 and 18 have orifices therein, spaced apart in positions for registering with orifices 19 formed in the tracks 6 and 6'. These orifices are adapted to be pinned together by piston operated pins, generally indicated at 20, carried by the respective blocks 13 and 16, having projecting pins in positions to pass through the orifices 19 in the tracks 6 and 6, and through the orifices in the portions 17 and 18, thereby to lock the heads 13 and 16 in adjusted positions with respect to the leg section 5.

The leg section 5 has ribs 5' extending lengthwise thereof and projecting generally at right angle to the body of the section. Secured on the lateral outer sides of the head portions 17 and 18 are sliding claws 115, FIG. 2 and FIG. 4, which grip the ribs 5 and act as a guide means thereon for the sliding blocks and prevent the jacking apparatus from swinging away from the column.

Each of the heads 13 and 16 is mounted by a hydraulicthreaded ram jack, one of which is illustrated generally at 21 and the other at 22. One form of spherical seat mounting for the hydraulic-threaded ram jack on the head is shown in FIG. 5, which is used for mounting each hydraulic-threaded ram and serves both as a mounting for the jack on the head and to effect universal movement with respect thereto.

As shown in FIG. 5, the lower end of the threaded ram 21, or 22, rests upon a support plate 23, which has a spherical face 24 upon a pad 25, supported by the head 13. These parts are held in place by a ring 26 secured by screws 27 to the head I3.

The lower end of the threaded ram 21 is provided with separate pins 28 inserted in radial holes 39 in the base of the ram 21 and in radial holes 29 in the surrounding rim portion of the plate 23 outside the base of the threaded ram 21. The pins 28 are separate from the ram and from the plate but form pin connections therebetween.

To clarify the attachment means of the threaded ram to the top of the jackhead (FIG. 5), the ring 26 is made in two pieces and surrounds the attached concave plate 23 at the end of the threaded ram. The threaded ram does not turn and the load is always a compression load on the spherical bearing block 25 bolted to the jackhead. The spherical bearing formed by the members 23 and 25 permits the necessary movement of the jackhead under the thrust of the threaded ram cylinder. There are no bearings other than this spherical seating. Pins 28 in holes 29 hold the concave upper plate to the jackhead. No pull will be exerted on this attachment means as the lower cylinders push the jackhead upward and the threaded rams are retracted under this opposed force on threaded rams through this attachment means.

The jack-climbing blocks 13 and 16 are attached to their respective jack tracks 6 and 6' by two hydraulically actuated pins 20. Each climbing block becomes a part of the leg structure, pinned in this manner, minimizing the moment that would be transmitted to the jack cylinders. To compensate for any lateral movement of the climbing block due to moment of the leg, the threaded ram 21, or 22, is attached to the climbing block 13, or 16, by a spherical seat, as shown in FIG. 5 and as described above. This attachment means permits the degree of moment that might take place without transmitting any stress to the threaded rod. The lower ends of the cylinders 7 and 8 are connected with the deck by clevis-attaching means, indicated at 9, permitting freedom of movement of the lower cylinders and thereby eliminating any lateral stress on the rods and the pistons in the cylinders.

The upper end portion of each threaded arm 21, or 22, extends into a hydraulic cylinder 30 secured by bolt fastenings connected with a flange 31 on the cylinder to the adjacent fixed support or deck 3, thereby holding the cylinder 30 in fixed position. Shock pads are shown at 48 (FIGS. 2 and 3) for holding the cylinder 30, and thereby the threaded ram 21 or 22, with respect to the deck, as for example, the deck 3. Provision is made for rotating the threaded rarn nuts 32 relative to the threaded rams 21 and 22 for effecting longitudinal movement thereof and with each of the adjacent connected heads 13 and 16, respectively. This means synchronizes the rotation of the nut with the illustratedthreaded ram movement and is power driven as by a small hydraulic motor operating a surrounding ring gear, as described in my aforesaid application, Ser. No. 678,397, now U.S. Pat. No. 3,495,808.

The application of the threaded ram to a jacking system for offshore barges is primarily for its safety advantages over plain cylinders. In the event of hydraulic failure, the holding capacity of the nut that rotates on the threaded ram is double the lifting capacity of the hydraulic pressure moving the ram in a linear direction. This ram does not turn, the nut rotates on the ram and turns at a speed that permits the ram to extend at a given speed by synchronized control. The threaded ram is basically a hydraulic cylinder that has hydraulic pressure applied to the head end, or the piston only. It is not a two-way cylinder and has no pressure applied to the ram end which is threaded.

An important safety factor incorporated in the controls of the system is the engagement and disengagement of the climbing block pins in their respective tracks. The pins cannot be pulled from both sets of climbing blocks at the same time. One set of pins and its climbing block will always be engaged to its respective leg track. The climbing block pins cannot be disengaged on one track until the pin's are engaged in the other adjacent track, the opposite climbing block.

In this system, the threaded rams have 400-ton push capacity on the jackheads 13 and 16 (FIG. 1). Their holding capacity is 800 tons each, with a safety factor of to 1 through the nuts 32 that extend inside the cylinders 30. The nut 32 is turned by a small hydraulic motor free of any load, and synchronized with the hydraulic pressure in the head end of the cylinder. The nut will stop turning under load. If it should run ahead of the advance of the ram, it would simply stall and when the free of load, it would again rotate under power of its hydraulic motor. The use of the threaded ram is therefore a safety factor that is not obtainable with an ordinary cylinder.

The plain two-way cylinders 7 and 8 in FIG. 1 are to augment the threaded rams and do not oppose them. The system in this instance shows a 700-ton capacity unit, but varied tonnage units can be employed. The threaded ram 21 or 22 has 400-ton push, in this instance, capacity at the head end of the jack cylinder. The hydraulic cylinders Jhave tons each pull capacity from their rod ends applied to the ears of the jackhead for a total of 700-ton capacity applied in a downward thrust on the jackhead slide, attached to the leg track. Since the threaded ram 30 has no return ability hydraulically, the lower cylinders 7 move the jackhead 13 and force the threaded ram to retract into the threaded ram cylinder 30. The speed of the nut turning on the threaded ram must synchronize with the speed of cylinders 7 in returning the jackhead for another stroke.

1n the form of the invention shown in FIGS. 1 and 3, each section or corner of the leg has a pair of cylinders 7 on each opposite side thereof. All of these cylinders 7 of all legs will work together to move the corresponding heads 13 pinned at 20 to the respective leg sections 5. During the operation of the cylinders 7 under load, the cylinders 8 of all leg sections are returning free of the leg tracks 6, the corresponding pins 20 of the heads 16 thereof being withdrawn during that operation. Conversely, when the cylinders 8 for all of the leg sections operate under load, all of the cylinders 7 are returning free of connection with the tracks 6 of the legs.

If desired, a tandem set of power cylinders can be utilized for each leg section, located between decks and operating on the leg section 5 in the same manner as described above. This tandem set of cylinders and jacks will be connected with the main set, as illustrated, to operate in synchronism therewith in the manner described above and requires a single track only for the leg section 5.

If desired, according to the load and the conditions to be encountered, both sets of cylinders 7 and 8 may be employed on both sides of the leg section 5, as shown in FIG. 4. Cylinders 7 would work alternately with the cylinders 8 in the manner described above to provide a stepping action along the length of the leg section 5 and to obtain relative movement between the leg and the platform.

The application of the hydraulic threaded ram to an offshore jacking system increases materially the safety and efficiency of elevating offshore drilling barges. I have described the jacking system as applied to each corner of a leg. The actual structure of the leg may vary considerably as may be found desirable.

In the form of the invention shown in FIGS. 1, 2 and 3, the jacks 8 are in a position to start a lifting stroke, while the jacks 7 have completed a lifting stroke. The load is shifted from the jacks 7 to the jacks 8 and, when the jacks 8 have completed their lifting stroke, these would be extended, while the jacks 7 would be contracted and are ready for engagement for their next lifting stroke. The load is being shifted continuously from the the jacks 8 to the jacks 7 and then back to the jacks 8 as this sequence continues, thereby doubling the speed of operation of the system so as not to lose time while the rods are extended to make another lifting stroke.

At any hydraulic failure or interruption of the jacking due to unforseen problems, the threaded ram 21, or 22, is capable of holding the barge at its attained position, The threaded rams, with their locking nuts 32, are the holding means in this system.

In jacking operation, the lifting load is shifted from the jackheads 16 to the jackheads 13 in uninterrupted climbing except in the pause that takes place in pulling and inserting the pins of the heads forming the climbing blocks 16 and 13 into their respective jack tracks. The pins cannot be pulled from both sets of climbing blocks at the same time. One set of pins and climbing blocks will always be engaged with respective leg track. For example, the pins cannot be removed from the climbing block on the track 6' until the pins are engaged in the opposite climbing block on the track 6.

The cylinders 7 and 8 return the climbing blocks 13 and 16 when free of engagement with their respective tracks 6 and 6' and push the threaded rams 21 and 22 back into their hydraulic cylinders. The conventional hydraulic motor rotating the ram nuts 32 operates in reverse, synchronized with the speed of the lower cylinders in their unattached return stroke.

The invention may be used with two distinct systems. One of these is a continuous jacking system and the other is a singleacting system that operates in a step-by-step method.

The continuous system uses double the number of jacking units, and is shown in FIG. 1 with two units 7 and 8 applied to a single leg section 5. If it is a three-cornered open structural fabricated pipe leg, six jacks would be usedtwo on each corner. These units would operate in' two groups, the three left-hand ones facing the corners would jack together and the three right-hand units together. While one group is lifting the load, the other group is retracted for a lifting stroke. The load of the barge is shifted from one set of jack units to the other with a slight dwell of movement to pull the pins from one set of jackheads, completing its stroke, and engaging the pins of the other set to carry the lifting load. It is in the continuous jacking system that the threaded ram plays its special role.

The continuous jacking system uses the holding capacity of the threaded ram as its locking device at all times. When jacking operations are completed, all jack units are engaged to the legs for double the holding capacity while the barge remains elevated above water. All jacks can be applied in the continuous jacking system for double the load-lifting capacity if required, for instance in pulling a leg that has penetrated deep into the bottom. The continuous jacking system would use eight jacks on a four-corner open leg, each four units working in unison. A continuous jacking system can also be used in pairs with opposed or opposite jacks working in uniform and on a cylindrical column, as in FIG. 7.

I have shown in FIG. 7 a column 33 having a plurality of radially projecting tracks 34 extending lengthwise thereof, there being four such tracks illustrated in the embodiment shown, and each having backup plates 35 to secure the connection of the track plate with the column. The track plate 34 is provided with spaced holes for selective engagement by the pins 36 of the respective heads.

Referring to FIGS. 6, 8 and 9, the support leg is indicated generally at 49, being shown as skeleton form, having cylindrical leg sections 50 disposed in a triangular relation. In this form of the invention, each of the leg sections 50 has a track 51 extending lengthwise thereof provided with spaced holes 52 at intervals for receiving the stepping pins, as described. Shock pads 48 also extend laterally from the leg sections 50 and are attached to the adjacent deck to anchor the hydraulic threaded ram jack 54 with respect thereto, which hydraulic threaded ram jack mounts a head 55, as shown in FIG. 8.

Referring to FIGS. 8 and 9, each leg section 50 has a track 51 provided with a track guide or raceway 101 which forms a part of the head 55. A clevis 102 attaches the lower cylinder to the deck 2 of the barge structure. A holding pin cylinder or block is indicated at 103 (see FIG. 6), having holding pins 104 with hydraulic actuators 105 for the pins. At the opposite side of the track guide 101, frame bracing 106 is provided, with frame bracing provided also on the deck 2. Frame openings are formed at 108 for variable locking positions of the holding pins 104. A hydraulic actuator is shown at 109 to move the holding pin block 103 for variable adjustments of the pin 104 in slots 108 to engage track pin holes 1 10 in the track 51.

In the single action system, according to FIGS. 8 and 9, it is desirable to have variable spaced holding positions to engage the holding pins, and attaching the barge to the legs for long holding periods. Although the threaded rams are capable of holding the load in question, the continuous jacking system with double the number of jacks, each threaded ram is only holding 50 percent of the load, each ram holds in the singleacting system. It is therefore advantageous and necessary to use a holding pin on the single-action system. The holding pin is made for varied locking positions as it is anticipated that the legs will penetrate the bottoms to varied depths and the pin holes in the track can vary from leg to leg. With varied openings in the holding frame and the holding pin movable to the hole that lines up with the track hole, the leg can be pinned at varied positions. The movable pin block 103 does not carry any of the barge load; it simply acts as a carrier for the pins 104 which hold the barge to the jack track with bearing holes on both sides of the jack track frame holding the load.

A pair of upright cylinders 56 are connected with the head 55 in the manner described above for raising and lowering the head in synchronism with the hydraulic threaded ram 54. Pins 57 lock the head to the track 51 in the stepped positions thereof engaging in holes 52 in the track.

The reason for using two hydraulic cylinders pulling on the jackhead and attached to the deck by clevis means is to balance the pull on the jackhead and distribute the load in exerting 700 tons, in this instance, of force in lifting the barge. Four hundred tons, in this instance, of thrust is pushed against the jack house roof by the threaded ram and 150 tons each is exerted on each ear of the jackhead for the combined pull of 300 tons on the barge deck combined with the 400 ton thrust from the jack house roof totaling 700-ton force on the jackhead pinned to the leg track. The capacity in tonnage for any unit can be more or less, depending on the size of the cylinders.

In reverse action, the two hydraulic cylinders 7 and 56 have 350-ton capacity each, in this instance, from their head end or compression stroke for a combined capacity of 700 tons for pulling the legs of the barge out of the bottom of the sea floor, and raising the legs. This system therefore has 700-ton working capacity in this instance in both directions when needed for each jacking unit. The size and capacity of the threaded rams and lower cylinders will vary in different capacity jacking systems.

A leg in the form ofa column is shown in FIG. 7, with ajack arrangement for a continuous jack system having two sets of jacks designated respectively at A and B. The jacks A operate in unison and the jacks B operate in unison.

The hydraulic pressure for the ram nut motors and the flow of hydraulic pressure to all cylinders can be synchronized to work these components in unison. Controls and lines for the hydraulic pressure are conventional and are not illustrated.

The power system for each set of jacks will be at each leg in their respective jack house. The hydraulic rams will be operated by a dual pumping system, powered by two hp. electric motors. One-half of the pumping system can operate the jacking rams at one-half their normal speed, which is desirable for controlled leveling, and for jacking in event of motor or pump failure on one of the two systems, adding extra power in the two pumping systems for operating safety.

While the invention has been illustrated and described in certain embodiments, it is recognized that other variations and changes may be made therein without departing from the spirit of the invention.

I claim:

1. Jacking apparatus for effecting relative vertical movement between a platform and an upright column leg having a track therealong, said jacking apparatus comprising a head, means for connecting the head step by step with the track, a pair of upright fluid power devices fixed at one end and con nected at the opposite end with the head, and a hydraulic threaded ram jack connected with the opposite side of the head, and means operatively connecting the threaded ram with the platform.

2. lacking apparatus according to claim 1, wherein the hydraulic-threaded ram jack is mounted with respect to the head and is extendable relative to the platform.

3. Jacking apparatus according to claim 1, wherein the track has spaced orifices therein, and means carried by the head for selective pin engagement with the track orifices.

4. Jacking apparatus for effecting relative vertical movement between a platform and an upright column leg having a track therealong, said jacking apparatus comprising a head, an upright hydraulic threaded rarn jack operatively connected at one end with the head and mounting the head, a nut on the threaded ram and movable thereon for movement of the head axially of the threaded ram cylinder, a pair of upright fluid power devices fixed at one end to the head for movement in conjunction with the hydraulic threaded jack, and means forming a step-by-step operative connection between the head and the track.

5. Jacking apparatus according to claim 4, wherein the track has orifices spaced at intervals therealong, and removable pins detachably engaging in the orifices for connecting the head step by step with the track.

6. J acking apparatus according to claim 4, wherein the head has side plates in embracing relation with the track and provided with orifices therein in positions to align with orifices in the track, and pins for detachably engaging in the respective orifices for detachably connecting the head with the track.

7. Jacking apparatus according to claim 4, wherein the hydraulic threaded ram jack has an end portion aligned with the head, a ring mounted on the head, and pin means interconnecting the ring with the end portion of the threaded ram for connecting said end portion with the head for universal movement relative thereto.

8. Jacking apparatus for effecting relative vertical movement between a platform and an upright column leg having a plurality of tracks extending laterally in different directions relative thereto and extending lengthwise of the leg, said jacking apparatus including a jacking unit for each of said respective tracks, each jack unit comprising a head having a portion extending in bearing relation with the track for movement therealong, means for connecting the head with the track in step-by-step positions, an upright hydraulic-threaded ram jack having one end supported by the platform and the opposite end operatively mounting the head, and a pair of upright fluid power devices mounted at opposite sides of the head and connected with the latter for acting in conjunction with the hydraulic-threaded ram jack.

9. Jacking apparatus according to claim 8, wherein the bearing portion and the track have aligned holes spaced at intervals therealong, and detachable pins for engaging in the holes to secure the head in adjusted position with respect to theleg.

l0. Jacking apparatus according to claim 8, comprising a single acting system having pin holes for receiving means to effeet the step-by-step action.

1 1. Jacking apparatus according to claim 8, having variable holding positions with holding pins, and means for moving the pms.

l2. Jacking apparatus according to claim 1, including clevises for securing the fluid power devices at one end to a stationary support.

13. Jacking apparatus in combination with a column and a platform guided on the column for movement longitudinally thereof, said jacking apparatus comprising a sliding block having means removably engaging the column for holding the platform relative to the column, at least one hydraulic cylinder having a cylinder end and a piston end, one of said ends being secured to the platform and the other end secured to the sliding block for movement of the block longitudinally along the column, a threaded cam connected with the sliding block and having means for locking the sliding block relative to the platform, and means connected with the platform for carrying the threaded ram.

14. Jacking apparatus according to claim 13, including a pair of hydraulic cylinders disposed side by side and each having a cylinder end and a piston end with one of said ends secured to the platform and the other end secured to the sliding block and urging the latter longitudinally relative to the column.

l5. Jacking apparatus according to claim 13, including means forming a spherical seat between the threaded ram and the sliding block for universal movement of the threaded ram relative to the sliding block.

16. Jacking apparatus according to claim 13, including a second sliding block mounted on the column for movement longitudinally relative thereto, at least one hydraulic cylinder having a cylinder end and a piston end with one of said ends secured to the platform and the other end secured to the sliding block for urging the same longitudinally along the column, a threaded ram connected to the second mentioned sliding block having means for locking said second mentioned sliding block relative to the platform, and means for operating the hydraulic cylinder alternately to effect step-by-step relative movements between the column and the sliding blocks. 

1. Jacking apparatus for effecting relative vertical movement between a platform and an upright column leg having a track therealong, said jacking apparatus comprising a head, means for connecting the head step by step with the track, a pair of upright fluid power devices fixed at one end and connected at the opposite end with the head, and a hydraulic threaded ram jack connected with the opposite side of the head, and means operatively connecting the threaded ram with the platform.
 2. Jacking apparatus according to claim 1, wherein the hydraulic-threaded ram jack is mounted with respect to the head and is extendable relative to the platform.
 3. Jacking apparatus according to claim 1, wherein the track has spaced orifices therein, and means carried by the head for selective pin engagement with the track orifices.
 4. Jacking apparatus for effecting relative vertical movement between a platform and an upright column leg having a track therealong, said jacking apparatus comprising a head, an upright hydraulic threaded ram jack operatively connected at one end with the head and mounting the head, a nut on the threaded ram and movable thereon for movement of the head axially of the threaded ram cylinder, a pair of upright fluid power devices fixed at one end to the head for movement in conjunction with the hydraulic threaded jack, and means forming a step-by-step operative connection between the head and the track.
 5. Jacking apparatus according to claim 4, wherein the track has orifices spaced at intervals therealong, and removable pins detachably engaging in the orifices for connecting the head step by step with the track.
 6. Jacking apparatus according to claim 4, wherein the head has side plates in embracing relation with the track and provided with orifices therein in positions to align with orifices in the track, and pins for detachably engaging in the respective orifices for detachably connecting the head with the track.
 7. Jacking apparatus according to claim 4, wherein the hydraulic threaded ram jack has an end portion aligned with the head, a ring Mounted on the head, and pin means interconnecting the ring with the end portion of the threaded ram for connecting said end portion with the head for universal movement relative thereto.
 8. Jacking apparatus for effecting relative vertical movement between a platform and an upright column leg having a plurality of tracks extending laterally in different directions relative thereto and extending lengthwise of the leg, said jacking apparatus including a jacking unit for each of said respective tracks, each jack unit comprising a head having a portion extending in bearing relation with the track for movement therealong, means for connecting the head with the track in step-by-step positions, an upright hydraulic-threaded ram jack having one end supported by the platform and the opposite end operatively mounting the head, and a pair of upright fluid power devices mounted at opposite sides of the head and connected with the latter for acting in conjunction with the hydraulic-threaded ram jack.
 9. Jacking apparatus according to claim 8, wherein the bearing portion and the track have aligned holes spaced at intervals therealong, and detachable pins for engaging in the holes to secure the head in adjusted position with respect to the leg.
 10. Jacking apparatus according to claim 8, comprising a single acting system having pin holes for receiving means to effect the step-by-step action.
 11. Jacking apparatus according to claim 8, having variable holding positions with holding pins, and means for moving the pins.
 12. Jacking apparatus according to claim 1, including clevises for securing the fluid power devices at one end to a stationary support.
 13. Jacking apparatus in combination with a column and a platform guided on the column for movement longitudinally thereof, said jacking apparatus comprising a sliding block having means removably engaging the column for holding the platform relative to the column, at least one hydraulic cylinder having a cylinder end and a piston end, one of said ends being secured to the platform and the other end secured to the sliding block for movement of the block longitudinally along the column, a threaded cam connected with the sliding block and having means for locking the sliding block relative to the platform, and means connected with the platform for carrying the threaded ram.
 14. Jacking apparatus according to claim 13, including a pair of hydraulic cylinders disposed side by side and each having a cylinder end and a piston end with one of said ends secured to the platform and the other end secured to the sliding block and urging the latter longitudinally relative to the column.
 15. Jacking apparatus according to claim 13, including means forming a spherical seat between the threaded ram and the sliding block for universal movement of the threaded ram relative to the sliding block.
 16. Jacking apparatus according to claim 13, including a second sliding block mounted on the column for movement longitudinally relative thereto, at least one hydraulic cylinder having a cylinder end and a piston end with one of said ends secured to the platform and the other end secured to the sliding block for urging the same longitudinally along the column, a threaded ram connected to the second mentioned sliding block having means for locking said second mentioned sliding block relative to the platform, and means for operating the hydraulic cylinder alternately to effect step-by-step relative movements between the column and the sliding blocks. 